Geographical mile
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The geographical mile, or U.S. survey mile, is a unit of length determined by 1 minute of arc along the Earth's equator, approximately equal to 1855 metres (6087.15 international feet).
(Wikipedia alert! mile page say it is 1609.347 metres!)
It is not the same as the more commonly used statute mile, which is 1609.344 metres (5280 feet), or the nautical mile which is 1 minute of arc along a great circle of the Earth (1852 metres, 6076.1 feet). The U.S. survey mile is used almost exclusively by the U.S. Coast and Geodetic Survey.
See also: